Air filter



FIG. 1 is a right perspective view thereof.

FIG. 2 is a left perspective view thereof.

FIG. 3 is a front view thereof.

FIG. 4 is a top view thereof.

FIG. 5 is a bottom view thereof.

FIG. 6 is a left side view thereof; and,

FIG. 7 is a right side view thereof.

The rear surface of the air filter is devoid of surface ornamentation and forms no part of the claimed design.

The broken lines illustrate portions of the air filter that form no part of the claimed design. 

CLAIM The ornamental design for an air filter, as shown and described. 